linux-kernel - Re: [PATCH 2/4] input: keyboard/mouse/touchscreen/misc: Use dev_get

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Message-ID: <20190703061746.GI4652@dell>
Date:   Wed, 3 Jul 2019 07:17:46 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Lothar Waßmann <LW@...O-electronics.de>
Cc:     Fuqian Huang <huangfq.daxian@...il.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Tony Lindgren <tony@...mide.com>,
        Richard Fontana <rfontana@...hat.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Fabio Estevam <festevam@...il.com>,
        Rob Herring <robh@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Anson Huang <anson.huang@....com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Luca Weiss <luca@...tu.xyz>,
        NXP Linux Team <linux-imx@....com>,
        Sylvain Lemieux <slemieux.tyco@...il.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Brian Masney <masneyb@...tation.org>,
        Arnd Bergmann <arnd@...db.de>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        linux-input <linux-input@...r.kernel.org>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Alexios Zavras <alexios.zavras@...el.com>,
        linux-tegra@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Allison Randal <allison@...utok.net>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Pascal PAILLET-LME <p.paillet@...com>,
        Shawn Guo <shawnguo@...nel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        H Hartley Sweeten <hsweeten@...ionengravers.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Olof Johansson <olof@...om.net>,
        Christian Hoff <christian_hoff@....net>,
        Enrico Weigelt <info@...ux.net>,
        Gabriel Fernandez <gabriel.fernandez@...com>
Subject: Re: [PATCH 2/4] input: keyboard/mouse/touchscreen/misc: Use
 dev_get_drvdata()

On Tue, 02 Jul 2019, Lothar Waßmann wrote:

> Hi,
> 
> On Tue, 2 Jul 2019 19:47:16 +0800 Fuqian Huang wrote:
> > Andy Shevchenko <andy.shevchenko@...il.com> 於 2019年7月2日週二 下午5:51寫道：
> > >
> > > On Tue, Jul 2, 2019 at 11:20 AM Fuqian Huang <huangfq.daxian@...il.com> wrote:  
> > > >
> > > > I am not an expert on this. I just write a coccinelle script to search
> > > > this kind of misuse and fix it in a naive way.
> > > > Could you tell me about how to use the proper bus accessors? Then I
> > > > will fix it up and resend a v2 patch set.  
> > >
> > > First, don't top post.
> > > And answering to this, simple drop the patch.
> > > Proper bus accessors is exactly what it's used in the current code.  
> > 
> > But why not use dev_get_drvdata directly.
> > It simplifies getting the 'driver_data' from 'struct device' directly.
> > And the platform_device here is not required.
> > Replace it can remove the unnecessary step back and forth. (dev -> pdev -> dev).
> > 
> Did you check whether the compiler generates different (better) code
> with and without your patch? My guess is it won't.

I can see Fuqian's point.  If bus APIs are preferred, maybe it would
be nicer if the function was adapted to accept a platform_device
instead?

Caveat: I haven't taken the time to look into the call-site details.
	This comment is based on just the patch alone.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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